The Celtic manager got his tactics spot on in the recent derby clash.
The Frenchman came on as a second half substitute, providing the Hoops with a bit of skill and composure in the middle of the park that allowed them to expose a stretched Gers defensive line.
Hay believes it was a perfectly timed move from the Celtic manager, allowing the Hoops to re-take control of the game.
"Rangers made some tactical adjustments of their own at half-time, and they had started to get a grip on the game in terms of possession without ever really threatening to equalise.
"While you only have a one goal lead though, you never know what can happen, and it was important that Lennon addressed the situation and took control of the game again. Bringing Ntcham on allowed Celtic to do exactly that."
What can Ntcham achieve this season?
Hay would later go on to praise the midfielder also, suggesting he is one of the most talented players in the Scottish game right now.
He does raise one worry though - his inconsistency. It's a fair criticism. Ntcham is not always at the top of his game and it's probably a trait that has held his Celtic career back to date.
It's also the reason he is not a regular starter for Lennon, who has preferred the central trio of Scott Brown, Callum McGregor and Ryan Christie.
Writing the 23-year-old off would be silly though. He's simply too talented.
Ntcham's big aim this season should be nailing down a spot in the heart of the Celtic engine room. If he does that it'll mean he has found real consistency and can take his Hoops spell to a new level.
That would be an exciting development for the Celtic manager.
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